1. The Field of the Invention
The present invention relates generally to the manufacture of carbon nanomaterials. More particularly, the present invention relates to methods for manufacturing carbon nanospheres that are highly dispersible in a polar solvent.
2. The Related Technology
Carbon materials have been used in various fields for a variety of applications. Examples of current uses of carbon materials include pigments, fillers, catalyst supports, and fuel cell electrodes, among others. Pyrolysis of organic compounds is a known method for preparing carbon materials. For example, carbon materials can be produced by pyrolyzing resorcinol-formaldehyde gel at temperatures above 600° C.
Most carbon materials obtained by pyrolysis of organic compounds at temperatures between 600-1400° C. tend to be amorphous or have a disordered structure. Obtaining highly crystalline or graphitic carbon materials can be very advantageous because of the unique properties exhibited by graphite. For example, graphitic materials can be thermally and electrically conductive.
Recently, methods have been developed to make highly ordered graphitic structures such as carbon nanotubes. One way to make graphitic nanostructures is to carbonize a carbon precursor (carbon gas or carbon resin) in the presence of a metal catalyst. The catalyst is typically a salt of iron, nickel, or cobalt that is mixed with carbon precursor and then heated. During the carbonization process, the carbon nanostructure grows from or around the catalytic metal to yield a well ordered structure. The metal catalyst can be removed from the carbon nanomaterial by treating with strong acids. Amorphous carbon can be removed using an oxidizing agent such as potassium permanganate.